Process of making superpolyamide films



June 13, 1944- o. HERRMANN ETAL 2,351,208

PROCESS OF MAKING SUPERPOLYAMIDEA FILMS Filed June 25, 11.941l

DRY/N6 W4/HEER U Famenne 13,1944 n y 2,351,208

UNITED Vsm'rizs lP'A'rlatl'l. OFFICE PROCESS OF MAKING SUPERPOLYAMIDE FILMS Otto Hermann, Wiesbaden, and Anton-Wundererand Hans Bttger, Wiesbaden-Biebrich, Germany; vested in the Alien Property Custodian Application June 25, 1941, Serial No. 399,750

v In Germany July 6, 1940 7,' Claims. (Cl, 18-57) The present invention relates to the producprovided with a reflux condenser, so that the tion of superpolyamide lms by the casting proc- Solvent boils gently- When Complete dissolution ess. i

It is already known to prepare superpolyamide Cast from hopper Il in the usuel manner, While films according to the casting process. For said het. onto en endless metal band-or Casting Wheel purpose alcoholic or aqueous-alcoholic solutions of ,l0 so aS t0 obtain a lm l2 having a thickness of mixedsuperpolyamides are suitably used as eastabout 0.1 mm. After having been dried at a .teming solutions, for instance solutions of superperature .of .70 C.-l00 C. the foil now substanpolyamdes kfor the manufacture of which en tially free from any solvent is removed from the amino-carboxylic acid on lthe one hand and a Casting Support; for after-drying` it is pesed by mixture of a diamine and a dicarboxylic acid on means 0f guide rollers I3 througha drying ehe-Inthe other hand have been used as parent.- ma.. Yber I4 which has likewise been heatedto 7U C.- terial. These compounds and other mixed super- 100 C. The foil may .then be rolled up- To polyamides may be dissolved by heating them with facilitate the illustration of the present invenaliphatic lalcohols or mixtures of alcohols and tion, the web or hlm l2 is Shown 1n the drawing water and the9 solution thus obtained may then @S passing direotly t0 apparatus suitable for Proebe cast in known manner so as to obtain lms. essing it to remove any tendency to Curl- Parts has occurred, the solution is ltered and then` On preparing superpolyamide lms according which have been cut out of such a web possess` to the casting process it turns out to be inconthe inconvenient property ef Strongly rolling.

.Venient that the lms after having been dried and gg To the surface of the foil which had been in removed from the casting supports tend to roll. eontwt With the Casting Supporta mixture of 4U p The foils roll in such a manner that the surface parte .of ethyl alcohol and 60 parts of Water iS which had been in contact with the casting sup- .applied at ordinary temperature by mean-S of a port turns outside. The tendency of rolling is roller or afelt soaked With the liquid at which the extremely strong and cannot be essentially infoil is passed along- Slleh Ineens are here'illusiluenced by a variation of the casting and drying trated as a roller |5,\Which dips into a bath of Said conditions. owing-to said tendency of rolling the mixture of ethyl 2.1001101 andwater in trough I6.

. further treatment of the mms involves many The web is then 4conducted along scrapers ll by diflculties, y t A.which the excess of the unilaterally applied mois- We have found that the afore-named draw- $0 'Lening agent is removed; directly afterwards the back may be overcome as follows: the lmscast Web passed, While being freely Suspended. in known manner are treated with a swelling `through a vertically mounted drying Chamber I8 agent on the side which had been in contact with [having a length of about 4 meters and wherein the` casting support; they are then' dried. ghot air of 90 C.100 C. introduced through pipe As swelling agents there may particularly be AI9 floWS ln opposite direotion to the Gollrse 0f the used allphaticalcohols, especially ethanol. The Web and is removed therefrom through pipe 20,v

alcohols may have a high content of water. A thus causing a rapid drying of the unilaterally mixture of 60 parts of Water and 40 parts of ethyl moistened web. After the afore-described treatalcohol may be usedin many eases, The nim' ment is complete the foil. has lost itsftendency moistened on one side is suitably dried with the 40 of rolling. Parts cut therefrom remain both under aid of hot air by passing lthe lmthroughv a 'the usual storing conditions anden storing' in the drying chamber. heat in the rhat condition or -show only extremely In order to more readily describe the present insignicant, no longer disturbing tendency of l invention there is attached hereto a sheet of drawrolling.

ings, Ithesingle ngure of which is a diagram- The process may beperformed with high speed,

matic representation of apparatus suitable for for instance with a speed of 20 meters per min practicing the process of the present invention'. ute. By altering the speed and the temperature l The following example serves to illustrate the of the moistening liquid as well as by a more or invention, but it is not intended to limit it less thorough removal of the excess of liquid by thereby: the mentioned Scrapers the effect attained by 25 parts of a mixed superpolyamide; obtained the after-treatment may be innuenced. The opti.- by condensing parts of the adipic acid salt of mum conditions required for each case may readhexamethylene-diamine with 40 parts of caproily be ascertained by some tests. lactam, are heated together with 56 parts of We claim: methanol and 19 parts of water in a stirring vessel 55 1. In the process of casting superpolyamlde lrns wherein a solution of a superpolyamide in a solvent is cast on a casting support and dried thereon and the dried ilrn removed from the support, the method for overcoming the tendency of rolling of the thus obtained lm which comprises treating the lm after its removal from the casting support only on the side which had been in Contact with said casting support with a liquid swelling agent, and then drying the thus treated lm by treating the thus treated side Vwith hot air at a temperature of 90-100" C.

. 3. A process as dened in claim l wherein said swelling agent comprises an aliphatic alcohol.

4. A process as defined in .claim 1 wherein said swelling agent comprises ethyl alcohol.

I said superpolyamide is a mixed superpolyamide obtained by condensing the adipic acid salt of hexamethylene diamine with caprolactam.

7. In the process of casting superpolyamide lms wherein a solution of a mixed superpolyamide obtained by condensing'the adipic acid salt of hexamethylene diamine with caprolactam in a solvent, is cast on a casting support and dried thereon and the dried film removed from the support, the method for overcoming the tendency of rolling of the thus obtained hlm-which comprises treating the film after its removal from the casting support only on the side which had been in contact with said casting support with a liquid swelling agent, and then drying the thus treated film by' treating the thus treated side with het air at a temperature of QG-100 C.

OTTO HERRMANN. ANTON WUNDERER HANS BOTTGER. 

